function background(){
            var largeur=screen.availWidth;
            var hauteur = screen.availHeight;
            if (largeur / hauteur > 1.5)
                {document.body.background = "images/chute.jpg";
                document.vlinkColor="#FFA020";
                document.linkColor="#FFA020";
                document.alinkColor="#FFA020";}
            else { document.body.background = "images/Dune.jpg";
                document.vlinkColor="blue";
                document.alinkColor="blue";
                document.linkColor="blue"; }
        }
 
function backResize(){
	$(document).ready(function() { 
		var $winwidth = $(window).width();
		$("bitmap_5.gif").attr({
			width: $winwidth
		});
		$(window).bind("resize", function(){ 
			var $winwidth = $(window).width();
			$("bitmap_5.gif").attr({
				width: $winwidth
			});
		 });
	});
	}
 
function $(nom) {
        return document.getElementById(nom);
    }